This laboratory is mainly concerned with the genetic and cellular regulation of the expression of variables and constant region antigenic determinants present on light and heavy chains of immunoglobulin molecules before and after immunization with specific haptens. Idiotypes or V-region structural antigenic determinants associated with specific antibodies (e.g. anti polyfructosan, anti phosphorylcholine, anti alpha 1-6 dextran) have proven to be very useful as genetic markers or phenotypes in studies of genetic and cellular regulation of immunoglobulin expression. The preparation of monoclonal antibody (hybridomas) carrying specific idiotypes provide sources of large amounts of monospecific antisera that are invaluable in identification of specific markers in studies of interaction of cells in immunoglobulin expression.